Generic Class and Function

class Box<T>(val value: T) {
    fun <U> map(f: (T) -> U): Box<U> = Box(f(value))
}

// Generic function with a type bound
fun <T : Comparable<T>> max(list: List<T>): T {
    var best = list[0]
    for (item in list) if (item > best) best = item
    return best
}

// Multiple bounds via `where`
fun <T> copyIfNotNull(src: T?, dst: T)
    where T : Cloneable, T : java.io.Serializable {
    /* ... */
}

fun main() {
    val intBox: Box<Int>    = Box(42)
    val strBox: Box<String> = intBox.map { it.toString() }
    println(strBox.value)                                // "42"

    println(max(listOf(3, 1, 4, 1, 5, 9, 2)))           // 9
    println(max(listOf("apple", "banana", "cherry")))    // "cherry"
}